1. Field of the Invention
This invention relates to a visible light and anaerobic curing composition for encapsulating the surface of the primer mix disposed in the primer cup, particularly for use in center fire ammunition.
2. Brief Description of Related Technology
Anaerobic curable compositions are known, as are anaerobic curable compositions having a secondary cure mechanism, such as ultraviolet curing. Such adhesives are widely used commercially. However, until now, anaerobic curable compositions having a secondary visible light cure mechanism remained unknown.
As noted, radiation curable anaerobic adhesive compositions are known. For instance, U.S. Pat. No. 4,533,446 (Conway) is directed to such a composition that includes an anaerobically curable monomer, cationic photoinitiator, a peroxide and a ferrocence-based anaerobic polymerization initiator. However, in practice, these compositions have poor pot life since the metal ion in the ferrocene compound acts to initiate anaerobic cure.
U.S. Pat. No. 6,136,880 (Snowwhite) is an example of a radiation curable composition for optical fiber coatings that employs an acylphosphine oxide photoinitiator, which themselves are disclosed in U.S. Pat. Nos. 5,218,009 and 5,534,559, and examples of which are commercially available from Vantico Inc., Brewster, N.Y. under the tradename “IRGACURE” 819 (bis(2,4,6-trimethyl benzoyl)phenyl phosphine oxide), for one.
In a commercial application, in which sealing against environmental contaminants is important, others have used solvent-based lacquers or dissolved polymers, like nitrocellulose, to coat the primer mix disposed in a primer cup in ammunition. See e.g. U.S. Pat. No. 1,879,278.
However, in these known methods, the use of solvent is not environmentally friendly or healthy to the worker handling these coating materials. In addition, the solvent tends to interact with the primer mix, rendering the primer mix contaminated and less efficient in use.
It would thus be desirable to provide a visible light curable composition to provide a protective barrier from environmental contaminants, particularly during storage, that does not suffer from these recognized shortcomings.